Merged text and graphics refers to text positioned beside or superposed over part of a graphics image. In other words, merged text and graphics denotes text and parts of graphics images which have the same vertical position relative to a page.
Page printers print merged text and graphics by storing the data describing the entire merged text and graphics image in memory, addressing each piece of data, and then printing the entire page. Accordingly, the order in which a host computer sends the data to a printer is unimportant. However, page printers require substantial memory.
To print merged text and graphics on a serial or scanning printhead printer, the data must be sorted by vertical position or by address. However, such printers usually have limited memory. When printing merged text and graphics, the printer's memory may fill up before the merged text and graphics is fully sorted. If, in such a case, the printer has received data defining part of a graphics image, the printer may have to print a part of the image in order to make room in memory for incoming text data. Accordingly, if the incoming text data is addressed to a prior position, the text character will be misplaced unless the printer can back up the paper.
To allow serial and scanning printhead printers to print merged text and graphics, the page on which the image is to be printed may be feed through the printer twice. The printer prints either the text or the graphics first, and subsequently prints the other. However, re-feeding paper is cumbersome and results in poor printer throughput.
This invention provides a method whereby merged text and graphics may be printed by a page, serial or scanning printhead printer without requiring the memory necessary for full page addressing, and without the necessity of creating separate graphics and text documents or re-feeding paper through the printer. This invention may also be used in conjunction with an invention of Mark D. Lund for a Bidirectional Graphics Printing Method, assigned to Hewlett-Packard and described in a copending U.S. patent application, Ser. No. 07/299,105, filed Jan. 19, 1989.